Flexible elongate device having a vibratory impact tip and method of its use

ABSTRACT

A flexible elongate device including a flexible elongate tubular member having proximal and distal extremities. A flexible coil spring is provided having proximal and distal extremities. The proximal extremity of the coil spring is secured to the distal extremity of the flexible elongate tubular member. A rounded tip is secured to the distal extremity of the coil spring. A flexible elongate element having proximal and distal extremities is disposed within said coil spring and extends longitudinally of the coil spring. The distal extremity of the flexible elongate element is secured to the rounded tip. A vibrator is secured to the proximal extremity of the flexible elongate element for imparting vibratory motion to the flexible elongate element to cause vibratory impact motion of the rounded tip in a direction longitudinal of the axis of the flexible elongate element.

This is a continuation, of application Ser. No. 07/983,837 filed Dec. 1,1992 now abandoned.

This invention relates to a flexible elongate device having a distalextremity with a vibratory impact tip and method particularly useful forcatheters and guide wires.

In certain medical procedures, as for example in angioplasty procedures,lesions or stenoses have been encountered in vessels which are difficultto cross because they totally or almost totally occlude the vessel.Thus, there is a need for a device which will make it possible topenetrate and to cross such stenoses or lesions.

In general, it is an object of the present invention to provide aflexible elongate device having a distal extremity with a vibratory tipand a method which can be utilized for penetrating and crossing stenosesor lesions which occlude vessels in a patient.

Another object of the invention is to provide a device and method of theabove character which can be utilized with a distal extremity which isflexible and which can be adjusted in stiffness.

Another object of the invention is to provide a device and method of theabove character in which distal extremity follows the path of leastresistance.

Another object of the invention is to provide a device and method of theabove character which will not perforate the vessel wall.

Another object of the invention is to provide a device and method of theabove character in which the distal extremity can be steered.

Another object of the invention is to provide a device and method of theabove character which can be utilized with catheters and/or guide wires.

Another object of the invention is to provide a device and method whichis particularly useful in crossing hard-to-penetrate lesions orstenoses.

Additional objects and features of the invention will appear from thefollowing description in which the preferred embodiments are set forthin detail in conjunction with the accompanying drawings.

FIG. 1 is a side elevational view of a device incorporating the presentinvention in the form of a balloon dilatation catheter.

FIG. 2 is a side elevational view of a device incorporating the presentinvention in the form of a guide wire.

FIG. 3 is a greatly enlarged cross-sectional view of the distalextremity of the devices shown in FIGS. 1 and 2.

FIG. 4 is a cross-sectional view taken along the line 4--4 of FIG. 3.

In general, the flexible elongate device incorporating the presentinvention consists of a flexible tubular member having proximal anddistal extremities. A flexible coil spring is provided which hasproximal and distal extremities. Means is provided for securing theproximal extremity of the coil spring to the distal extremity of theflexible elongate tubular member. A rounded tip is secured to the distalextremity of the coil spring. A flexible elongate element havingproximal and distal extremities is disposed within the coil spring andextends longitudinally of the coil spring. Means is provided forsecuring the distal extremity of the flexible elongate element to therounded tip. Means is secured to the proximal extremity of the flexibleelongate element for imparting vibratory motion to the flexible elongateelement to cause vibratory motion of the rounded tip in a directionparallel to the longitudinal axis of the flexible elongate element.

More in particular as shown in FIG. 1, the device of the presentinvention takes the form of a balloon dilatation catheter 11 whichconsists of a flexible elongate member 12 having proximal and distalextremities 13 and 14 and a lumen 16 extending from the proximal to thedistal extremity an inflatable balloon 17 is mounted on the distalextremity 14. A hole 18 is provided in the flexible elongate member 12which establishes communication between the interior of the balloon 17and the lumen 16. A control mechanism 21 is mounted on the proximalextremity 13. The control mechanism 21 is provided with a tube 22 whichis in communication with the lumen 16 so that a fluid can be supplied tothe lumen for inflating and deflating the balloon 17.

The flexible elongate member 12 and the control mechanism 21 aresubstantially the same as described in the co-pending application, Ser.No. 07/983,899, filed Dec. 1, 1992 (A-57371), now abandoned. Asdisclosed therein, the control mechanism 21 includes a linearpotentiometer (not shown), the slider of which is controlled by acontrol member 26 which is movable longitudinally of the controlmechanism. A cable 27 extends from the control mechanism 21 and isconnected to a joystick control 28 which includes a joystick 29 forcontrolling the movement of the distal extremity of the balloondilatation catheter 11 as hereinafter described. Another cable 31connected to the control mechanism 21 is connected to a power supply 32.The power supply 32 is provided with a control knob 33 for a rheostat(not shown) provided within the power supply 32.

The balloon dilatation catheter is provided with a distal extremity inthe form of a coil spring assembly 36, the details of which willhereinafter be described.

Another embodiment of the device of the present invention is shown inFIG. 2 which takes the form of guide wire 41. The guide wire 41 consistsof a flexible elongate member 42 having proximal and distal extremities43 and 44 and having a bore 46 extending from the proximal extremity 43to the distal extremity 44. The flexible elongate member 42 is formed ofa suitable material such as a stainless steel tube as described inco-pending application, Ser. No. 07/983,899, filed Dec. 1, 1992(A-57371).

A control mechanism 41 substantially identical to the control mechanism21 is mounted on the proximal extremity 43 and differs from the controlassembly 21 by the omission of the tube 22. The distal extremity of theguide wire 41 carries a coil spring assembly 36 of the same type ascarried by the distal extremity of the balloon dilatation catheter 11.The coil spring assembly 36 is secured to the distal extremity 14 of theflexible elongate member 12 or the distal extremity 44 of the flexibleelongate member 42 by suitable means such as an epoxy in the case ofadhering the same to a plastic tubular member 12 for a catheter or bywelding 51 in the event of a stainless steel hypotube 42 for the guidewire.

The coil spring assembly 36 consists of an elongate tapered coil spring56 having proximal and distal extremities 57 and 58. The coil spring 56is formed of a suitable radiopaque material such as a platinum-tungstenalloy or palladium. The coil spring 56 can be of a suitable diameter, asfor example for a guide wire tapering from an outer diameter of 0.014"to 0.008" and for a catheter commencing with an outside diameter of0.35" to a minimum diameter at the distal extremity of 0.015". Theproximal extremity 57 is secured to the flexible elongate member 12 ofthe flexible elongate member 42 in the manner hereinbefore described. Arounded tip 61 is provided as a part of the coil spring assembly 36 andalso is formed of a suitable radiopaque material such as gold orstainless steel. Means is provided for securing the rounded tip 61 tothe coil spring assembly 61 and consists of a flexible elongate elementwhich is disposed within the interior of the tapered coil spring 56 andextends longitudinally thereof. The flexible elongate element 62 isprovided with proximal and distal extremities 63 and 64. The flexibleelongate element 62 can be formed of a suitable material such asstainless steel. Alternatively, it can be formed of a shape-memory alloyelement. The distal extremity 64 is bonded to the rounded tip 61 asshown in FIG. 3. Alternatively it can be soldered to tip. In addition,the rounded tip 61 is secured to the distal extremity 58 of the taperedcoil spring 56 by suitable means such as solder 66.

In order to permit reciprocatory movement of the flexible elongateelement 62 in a direction substantially parallel to the longitudinalaxis and to minimize frictional engagement with the flexible elongateelement 62 during such movement, the flexible elongate element 62 isslidably mounted within a tube 71 formed of a suitable material such asa flexible plastic such as polyethylene. By way of example, the flexibleelongate element 62 can have a suitable diameter, as for example0.005"-0.008" and is disposed within a tube 71 having an inside diameterof 0.009" and having a wall thickness of 0.001". The tube 71 extendssubstantially the entire length of the tapered coil spring 56 and hasits distal extremity secured within the distal extremity of the coilspring 58 by suitable means such as an epoxy 72.

Means is provided for imparting vibratory reciprocatory movement of theflexible elongate member 62 in the form of a solenoid 76. The solenoid76 consists of a cylindrical coil 77 formed of conducting wire andsegmented pole pieces 78 and 79 which are wrapped around the coilwinding 77 as shown particularly in FIGS. 3 and 4. The solenoid 76 isprovided with a bore 81 through which a plunger 82 formed of a suitablemagnetic material such as steel extends. The plunger 82 is provided withan outwardly swaged proximal end 83 and outwardly swaged distal end 84as shown particularly in FIG. 3. Means is provided for bonding theproximal extremity 63 of the flexible elongate element 62 into theswaged end 84 of the plunger 82 such as by the use solder 86. Theproximal swaged end 83 of the plunger 82 is swaged to provide a stop toprevent the plunger from passing out of the bore 81. In this manner, theplunger 82 in conjunction with the flexible elongate element 62 servesas a safety ribbon or element for the rounded tip 61 to prevent it fromseparating from the distal extremity of the tapered coil spring 56.

In the event that the flexible elongate element 62 is in the form of ashape-memory alloy element, it is necessary to supply electrical energyto that element. This can be accomplished by use of an insulatedconductor 91 connected to the proximal extremity 83 of the plunger 82 bysuitable means such as solder 92 so that the plunger 82 can serve as aconductor leading to the shape-memory alloy element 62. The conductor 91can be provided with a strain relief coiled portion 91a to permit theplunger 82 to reciprocate within the solenoid 76.

Since it is desirable that the distal extremity of the catheter 11 or ofthe guide wire 41 be steerable, four circumferentially spaced-apartelements 96, 97, 98 and 99 have been provided which have a negativecoefficient of expansion and extend interiorally of the tapered coilspring 56. Their distal extremities are secured in the epoxy 72 and areelectrically connected to an insulated return conductor 101. Theelements 96-99 are connected to conductors (not shown) which extend tothe proximal extremity of the flexible elongate member 12 or theflexible elongate member 42 and are connected through the cable 27 tothe joystick control 28. The return conductor 101 also extends to theproximal extremity of the flexible elongate members 12 or 42 and isconnected through the cable 27 to the joystick control 28. In thismanner, the distal extremity of the catheter 11 or the guide wire 41 canbe controlled in the manner described in co-pending application, Ser.No. 07/983,899, filed Dec. 1, 1992 (A-57371).

A pair of additional conductors 106 and 107 are connected to thesolenoid coil 77 and extend from the distal extremities 14 or 44 of theflexible elongate members 12 or 42, respectively, to the proximalextremities 13 and 43 of the same and extend through the controlmechanism 21 and are connected into the cable 31 connected to the powersupply 32. The power supply includes a rheostat (not shown) which iscontrolled by a knob 33 which controls the amount of current which issupplied to the solenoid to thereby adjust the magnetic forces appliedto the plunger.

Operation and use of the device with a vibratory impact tip may now bebriefly described in conjunction with the method of the presentinvention. Let it be assumed that the catheter 11 or the guide wire 41has been introduced into a vessel of the patient, as for example throughthe femoral artery of the patient and that the distal extremity has beenadvanced into a coronary artery by steering the same by the use of thejoystick 29 on the joystick control 28. Let it be assumed that thedistal extremity 36 has been advanced so that it has reached a stenosisin the vessel which it is unable to cross. At this time, thecardiologist can operate the control knob 33 to turn on the vibrator inthe form of the solenoid 76 to supply current through the conductors 106and 107 to the coil 77 in an interrupted manner by use of conventionalcircuitry such as a switching transistor driven by a square waveoscillator to cause reciprocatory motion against the yieldable force ofthe coil spring 56. Thus, there is created a high frequency vibrationranging from 10 Hz to 100 KHz which is applied to the tip 61 to causethe tip to penetrate the stenosis in the vessel. The rounded tip willcause the tip to follow the path of least resistance through thestenosis rather than through the vessel wall because it is normallydisposed at right angles to the direction of longitudinal vibration ofthe tip 61. The amplitude of the vibrations can be increased ordecreased depending upon the positioning of the control knob 33. In thismanner, it should be possible for the tip 61 of the coil spring assembly36 to penetrate the most difficult lesion or stenosis and to cross thesame. After this has been accomplished with a guide wire 41, a balloondilatation catheter of a conventional type can be inserted over theguide wire 41 and introduced through the stenosis so that the balloon isin alignment with the stenosis. The balloon 17 can be inflated fordilating the stenosis like in a conventional angioplasty procedure.After the appropriate dilation has been accomplished, the balloondilatation catheter and the guide wire 41 can be removed.

If a balloon dilatation catheter 11 having a coil spring assembly 36forming the distal extremity thereof is utilized, the catheter 11 can beinserted without the use of the guide wire and advanced to the stenosisby use of the joystick control 28, after which the control knob 33 canbe operated to cause vibratory impact motion of the tip 61 to occur tocause the tip 61 to cross the stenosis or lesion in the vessel and topermit the catheter 11 to thereafter be advanced to bring the balloon 17into alignment with the stenosis. After the balloon is in the properposition, it can be inflated and deflated by introducing a fluid intothe tube 22 in a conventional manner.

It should be appreciated that when the flexible elongate element 62 isin the form of a shape-memory alloy element, the stiffness of it can beincreased to ensure that the reciprocatory forces generated by thesolenoid 76 are transmitted to the tip 61. This can be accomplished bymoving the control member 26 to advance the slider to cause additionalcurrent to be supplied through the shape-memory alloy element 62 tostiffen the same as its temperature is increased.

It is apparent from the foregoing that there has been provided aflexible elongate device which has a distal extremity with a vibratingimpact tip which can be utilized to penetrate and across difficultlesions or stenoses in a vessel of a patient. This is particularlyimportant because it reduces the possibility of the patient having toundergo bypass surgery.

What is claimed is:
 1. A flexible elongate device comprising a flexibleelongate tubular member having proximal and distal extremities, aflexible coil spring having proximal and distal extremities, meanssecuring the proximal extremity of the coil spring to the distalextremity of the flexible elongate tubular member, a rounded tip securedto the distal extremity of the coil spring, a flexible elongate elementhaving proximal and distal extremities disposed within said coil springand having an axis extending longitudinally of the coil spring, meanssecuring the distal extremity of the flexible elongate element to therounded tip and means secured to the proximal extremity of the flexibleelongate element for imparting vibratory motion to the flexible elongateelement to cause vibratory impact motion of the rounded tip in adirection longitudinal of the axis of the flexible elongate element. 2.A device as in claim 1 wherein said means secured to the proximalextremity of the flexible elongate element is in the form of anelectrically actuated solenoid having a plunger, wherein said flexibleelongate element is secured to said plunger and wherein said solenoid isprovided with means for retaining said plunger in said solenoid, saidflexible elongate element serving as a safety wire for retaining therounded tip on the distal extremity of the coil spring.
 3. A device asin claim 2 wherein said means secured to the proximal extremity of theflexible elongate element includes a power supply connected to thesolenoid for supplying electrical energy to the solenoid and controlmeans connected to the power supply for adjusting the amount of energysupplied to the solenoid to adjust the impact provided by the roundedtip.
 4. A device as in claim 1 wherein said flexible elongate element isin the form of a shape-memory alloy element together with electricalmeans connected to the shape-memory alloy element for supplying currentto the shape-memory alloy element to increase the stiffness of theshape-memory alloy element.
 5. A device as in claim 2 together with atube disposed within the spring and having a bore therein through whichthe flexible elongate element extends and serving to minimize thefriction encountered by the flexible elongate element as it isreciprocated by the solenoid.
 6. A device as in claim 1 together with aplurality of circumferentially disposed flexible elongate elementshaving a negative coefficient of expansion disposed within the interiorof the coil spring and having distal extremities secured to the distalextremity of the coil spring and conductive means for supplying energyin the form of electrical currents to the plurality of flexible elongateelements having a negative coefficient of expansion and control meansfor adjusting the electrical currents supplied through the plurality offlexible elongate elements having a negative coefficient of expansion tocause steering of the distal extremity of the coil spring.
 7. A deviceas in claim 1 wherein the flexible elongate tubular member is in theform of a catheter together with an inflatable balloon mounted on thedistal extremity of the catheter and means carried by the flexibleelongate member for inflating and deflating the balloon.
 8. A method forcrossing a stenosis of a totally or almost totally occluded vessel of apatient by the use of a flexible elongate device having proximal anddistal extremities and having a coil spring with proximal and distalextremities with the proximal extremity of the coil spring secured tothe distal extremity of the flexible elongate device and a rounded tipsecured to the distal extremity of the coil spring and electricallyactuatable means carried by the distal extremity of the flexibleelongate device and connected to the rounded tip for imparting vibratorymotion to the rounded tip comprising advancing the rounded tip of thedevice into the vessel into contact with the stenosis, supplyingelectrical energy from the proximal extremity to the electricallyactuable means at the distal extremity of the flexible elongate deviceto generate substantially undamped vibratory motion solely at the distalextremity of the flexible elongate device so as to impart vibratorymotion to the rounded tip to facilitate advancement of the rounded tipthrough the stenosis to form a passage through the stenosis withoutdanger of penetrating the wall of the vessel.
 9. The method as in claim8 wherein said device is a guide wire together with a balloon dilatationcatheter having a balloon, further comprising the steps of inserting theballoon dilatation catheter over the guide wire to advance the balloonof the balloon dilatation catheter into and through the stenosis andinflating and deflating the balloon to enlarge the passage through thestenosis and thereafter withdrawing the balloon dilatation catheter andthe guide wire.
 10. A method as in claim 8 wherein said device is in theform of a balloon dilatation catheter having a balloon furthercomprising the steps of advancing the balloon dilatation catheter intothe passage in the stenosis after the tip has crossed the stenosis sothat the balloon is in registration with the stenosis and inflating anddeflating the balloon to increase the size of the passage through thestenosis and thereafter withdrawing the balloon dilatation catheter. 11.A method as in claim 8 wherein the vibratory motion is imparted in adirection which is generally parallel to the vessel wall.
 12. A flexibleelongate device for crossing a stenosis of a totally or almost totallyoccluded vessel of a patient comprising a flexible elongate tubularmember having proximal and distal extremities, a flexible coil springhaving proximal and distal extremities and having an axis, meanssecuring the proximal extremity of the coil spring to the distalextremity of the flexible elongate tubular member, a rounded tip securedto the distal extremity of the coil spring, electrically actuatablemeans carried by the distal extremity of the flexible elongate tubularmember and connected to the rounded tip and means for supplyingelectrical energy from the proximal extremity of the flexible elongatetubular member to the electrically actuable means at the distalextremity of the flexible elongate tubular member to generatesubstantially undamped vibratory motion solely at the distal extremityof the flexible elongate tubular member which is imparted to the roundedtip in a direction longitudinal of the axis of the coil spring.